1. Field of the Invention
The present invention relates to a welding method of a connection terminal piece to an end portion of lead wires which are led out from a deflection yoke coil for deflecting electron beams of cathode ray tubes in all types of color picture tube devices such as TV sets and monitors of personal computers, or which are led from any magnetic field generating assembly which comprises a winding of one of more lead wires each of which consists of a core having a coating layer of a high thermal-resistant insulation layer and a self fusing adhesive layer. More particularly, the present invention relates to a welding method of a connection terminal piece for a deflection yoke coil and the structure thereof for maintaining an optimal welding condition in order to provide a good conduction between the cores of the lead wires and the connection terminal piece, as well as being capable of mass production due to reduction in number of manufacturing processes to be performed for the connection terminal piece and also being possibly performed by a mechanically automated system capable of performing the entire processes for manufacturing a deflection yoke coil.
2. Background Information
In prior art, a manufacturing method of a deflection yoke coil or a magnetic field generating assembly generally comprises steps of winding one or more wire bundles on a winding tool in order for the wire bundles to be formed in a desired shape. The respective wire bundle is made of one or more properly twisted lead wires each of which consists of a core having a coating layer of a self fusing layer and a high thermal-resistance insulation layer therearound. The formed wire bundle is patterned into a winding body by a fusing method through heating by means of electric conduction. Specifically, the patterning step comprises substeps of maintaining the wire bundle in a wound status; hardening the wire bundle; and plasticising the wire bundle. The process for patterning the winding body may be performed mechanically and automatically by an automated winding system.
In the prior art as shown in FIG. 1, one deflection yoke coil 30, which is a sort of a winding body consisting of one or more wire bundles, surrounds around a deflection yoke 20 which is fixed to a neck portion 10 of, e.g., a Braun tube, and is integrally combined with a ferrite core 40. The deflection yoke coil 30 is electrically connected to a printed circuit board 50 for the deflection yoke 20, through an end portion of lead wires 31 which are led out from one or more wire bundles for the deflection yoke coil 30. The lead wires 31 may also be used as a power connection terminal for supplying electric current to a winding body when performing a process for patterning the winding body by a fusing method through heating by means of electric conduction as described above.
As also described above, the lead wires 31 for providing an electrical connection for the deflection yoke coil 30, each of which is made of a core having a coating layer of a self fusing layer and a high thermal-resistance insulation layer therearound, have a properly twisted form. The end portion of the lead wires 31 is connected to a connection terminal piece 32 in order to permit the lead wires 31 to be used in an automated streamline of a winding system, i.e., more specifically, in order to connect the lead wires 31 to a pair of clipper-type power supply terminals set up at a predetermined position in the automated streamline and thereafter to align the lead wires 31 to each other and connect them to a printed circuit board to be in a conductive condition.
FIG. 3a shows an embodiment of a known deflection yoke coil having a connection terminal piece. Referring to FIG. 3a, a connection terminal piece 32 is welded to an end portion of the lead wires 31 which are led out from a winding body of the deflection yoke coil 30. The welding of the terminal piece 32 to the end portion of the lead wires 31 can be performed by a typical spot-welding method. More particularly, a self fusing layer and an insulation layer of the lead wires 31, where the respective outer surface of the lead wires has a coating layer of both a high-thermal resistance insulation layer and a self fusing layer thereon (both insulation layer and self fusing layer are hereinafter referred to as "a coating layer"), are eliminated by a burning method which will be described in detail below and then the lead wires 31 are aligned with each other. The aligned lead wires 31 are wrapped up with the connection terminal piece 32 having a narrow-folded band form. Then, the connection terminal piece 32 is welded to the lead wires 31 by a pressure-welding method, where heat generated from electric current between a positive electrode rod and a negative electrode rod of the spot-welding machine is used for welding the connection terminal piece 32 to the lead wires 31 as the electrode rods make a pressure on the connection terminal piece 32.
In the prior art described above, the connection terminal piece 32 which is welded to the lead wires 31 is cut out from the lead wires 31 by a separate cutting process, after completion of the process for patterning the winding body in order to provide for a power supply terminal. Then, as shown in FIG. 3b, the coating layer of the end portion of the remaining lead wires 31 without the connection terminal piece 32 is eliminated by a burning method. More detailed explanation will be described below, with reference to FIGS. 4 and 5.
FIG. 4 shows an enlarged view of a prior art structure where a connection terminal piece is welded to the end portion of one or more lead wires for a deflection yoke coil. FIG. 5 shows an enlarged cross-sectional view of a lead wire. As shown in FIG. 5, one lead wire 31-1 consists of a core 31-2 having a coating layer of a high thermal-resistant insulation layer 31-3 and a self fusing layer 314. A core 31-2 may be made of copper or an alloy containing copper. The insulation layer 31-3 surrounds the core 31-2, and the self fusing layer 314 surrounds the insulation layer 31-3. After the respective insulation layers and the self fusing layers are eliminated from lead wires by a burning method through heating at high temperature, the remaining cores of the lead wires for the deflection yoke coil are re-processed as a connection terminal for electric connection of the cores to the printed circuit board 50 for the deflection yoke 20, as shown in FIG. 1. However, in this prior art, it is difficult to easily perform the process for eliminating the coating layer by a burning method.
Further, it is practically impossible to use the cut-off lead wires 31 having the connection terminal piece 32 as a connection terminal for connecting the cores of the lead wires 31 to the printed circuit board 50. This is because there may be a high possibility that the contact surfaces (conductive area) between the cores and the connection terminal piece 32 are partially non-uniform so that the connection condition between the lead wires 31 and the connection terminal piece 32 is very unstable. In addition, in the prior art technology, there exist problems such as undesirable power supply through the contact surfaces between the cores and the connection terminal piece 32, instability when patterning a winding body of the deflection yoke coil 30, and as a result non-uniformly fused adhesion of the deflection yoke coil to the winding body. Another problem in the prior art technology is that a deflection yoke coil is subject to being damaged so that a corona discharge may occur at the electric connection portion if an undesirably fused deflection yoke coil is used, because electric power is supplied to the deflection yoke coil usually by a power source operating at a high frequency. There are further problems in the prior art technology that the path of electrons emitted from an electron gun cannot be exactly controlled due to using a non-uniformly fused adhesion of the deflection yoke coil to the winding body so that picture quality has been lowered, which would influence an adverse effect to the quality of any electric items employing this faulty deflection yoke coil.
Now returning to FIG. 2, a flow-chart for prior art processes for manufacturing a deflection yoke coil is illustrated. The example shown in FIG. 2 will be described starting from a step of welding a connection terminal piece to the lead wires, which is prior to the step of patterning a winding body after making lead wires 31 to be wound on a winding tool in a desired winding body. The lead wires which are led out from the winding body are wrapped up, at a predetermined position thereof, by a connection terminal piece having a narrow-folded band form. Then, the connection terminal piece is welded to the lead wires by a spot-fusing method known in the art, where upper and a lower portions of the connection terminal piece are pressed by a positive electrode rod and a negative electrode rod of a spot-welding machine (not shown). The welding process of the connection terminal piece is terminated by connecting the connection terminal piece to the cores of the lead wires through a welding method, after the respective high thermal-resistant insulation layers and self fusing layers (referred to 31-4 and 31-3 in FIG. 5) of the lead wires are burnt down and eliminated sequentially by heating at a high-temperature through electric current derived from the electrode rods. After that, a process of patterning the winding body is performed where the lead wires led out from the wiring body for a deflection yoke coil are connected to clipper-type power supply terminals so that the respective self fusing layers of the lead wires are fused to be self bonded to each other by a heating method through electric current. After completing the patterning process of the winding body, a cutting out process is completed by cutting out an end portion of the lead wires being disposed at a position between the deflection yoke coil and the connection terminal piece and proximate to the connection terminal piece.
Following the cutting-out process, a burning process is performed where the respective coating layers at the remaining end portion of the lead wires without the connection terminal piece are eliminated by a burning method. An example of the burning method may be one of a stripping method, a heating method with a high frequency induction, a soldering method, a heater method or a spot-welding method, etc., all of which are known to a person skilled in the art. Even after completion of the burning process, burnt residues of the respective coating layers still exist at the end portion of the remaining lead wires and thus a clearing process for eliminating the burnt resides forcibly by using, e.g., a rotatable brush, etc. is performed.
As a result of the clearing process, the cores at the end portion of the lead wires are exposed. Then, a core winding process is performed where the exposed cores are tied up by a manual winding method to a connection terminal pin which is formed on a printed circuit board for the deflection yoke coil. Then, the core portion of the remaining lead wires that protrudes outward from the connection terminal pin is also cut out. After that, an immersion-type soldering process is performed where the connection terminal pin wound by the cores of the remaining lead wires is immersed into fused lead (Pb). Thus, manufacturing processes of a deflection yoke coil are completed.
As can be seen from the above description, the manufacturing process of a deflection yoke coil in the prior art needs several steps to be performed. As a result, prior art manufacturing of a deflection yoke coil takes a relatively long period of time and results in relatively low productivity. These factors cause a high manufacturing cost and a weak competitiveness in price.
In addition, an environmental condition in terms of sanitation in a factory becomes poorer due to an occurrence of dust during the clearing process of the burnt residues residing around the cores of the lead wires. Further, the conductivity of the lead wires may become poorer due to an oxidation thereof Also, soldering may be made frequently in a poor condition, which will lead to an adverse effect on the quality of the deflection yoke and any electric items employing the deflection yoke. More particularly, there is a severe problem in the prior art that because the core winding process for electrically connecting the exposed cores to the connection terminal pin formed on a printed circuit board can be performed only through manual working, the connection work is very difficult. Therefore, it is substantially impossible to accomplish a full automation for performing the entire processes for manufacturing a deflection yoke coil mechanically and automatically.